Nowadays, integration of electricity generation from renewable energy resources into power systems is increasing. As the renewable energy resources have uncertainty nature, the electricity generation from the renewable energy resources has the characteristics of output power fluctuation which causes impacts on voltage stability and frequency stability of the power systems.
In order to mitigate the impact of output power fluctuation, conventional generators in power systems become to have a fast load-following capability. In addition to a conventional pump-water storage hydro generator, a high-speed turbine generator such as a gas turbine generator, a steam turbine generator, can satisfy for the fast load-following capability. Due to affordable initial cost and low emissions of green house gas, the gas turbine generator can be considered as one of the best generator systems to smooth the fluctuation. However, the gas turbine may suffer stress if they are operated to response the fast fluctuation.
A prior art in this technical field is disclosed by US2012/0104842A1. This publication describes that the use of an auxiliary power source to reduce or substantially prevent the buildup of torque oscillations in the mechanical drive train in an aero gas turbine while providing electrical power to meet changes in an electrical condition of an isolated electrical network.
This prior art is only suitable for the isolated electrical network as terminal voltage cannot be kept at fixed level. Moreover, this prior art still requires an external electrical network to transport the electrical power and does not increase a capability of reactive power and active power.
Thus, there is a need for the auxiliary power source to increase the capability of reactive power and improve active power response of gas turbine generator in electric power systems where improvement of voltage and frequency stability is required.